Field of the Invention
This invention relates to embedded conduits as used to provide above-ground access to a valve, or the like, that is below ground and, more particularly, to a method for forming exposed upper surfaces around access regions of the conduits.
Background Art
Conduits are used at many different locations to provide above-ground access to different below ground components, such as valve actuators or switches associated with utility supplies, or other components that may control delivery of different consumable resources to residences and/or businesses. These conduits may be embedded in ground material on private property, in parkways, and/or on public roadways.
Embedded conduits on public roadways present a particular challenge, both at the time when the roadway is initially surfaced and when it is re-surfaced and/or repaired. Resurfacing of roadways with asphalt generally results in an end product wherein the upper surface is raised. In one typical process, the initial step of resurfacing involves removing a predetermined thickness of the existing asphalt through a milling process to create a generally level grade prior to application of a new asphalt layer. Different designs have been devised for these conduit systems that allow them to be adapted to a raised upper roadway surface.
In one form, the upper region of the conduit is provided with an access assembly having a diameter enlarged relative to the diameter of a main conduit portion that defines an access passageway extending from above ground to the particular operating site underground. A removable cover, generally intended to be substantially flush with grade when installed, is provided as part of the access assembly. The conduit consists of threadably engaged parts which can be turned relative to each other in opposite directions around a vertical axis to effectively raise and lower the height of an upper edge of the access assembly at which the cover is located.
The above design, while conceptually sound, often becomes inoperable or impractical because of the nature of the material making up its parts. Typically, the threadably engaged parts and the cover are made from cast iron. These parts may be immersed in water, in some environments at almost all times. As a result, the parts are prone to rusting and corroding. This may cause the parts to fuse to the point that when attempts are made to relatively turn the threaded parts, the operator may be unable to do so. Alternatively, large torques applied to the threaded parts may cause a failure at one or more locations along the conduit. In a worst case, torquing of the parts may cause a failure of an underground valve, or the like. Any of the above results could result in a time-consuming and potentially expensive repair. In a worst case, the conduit assembly may have to be unearthed to gain access to an underground component being controlled.
As an alternative to this design, it is known to provide a collection of extension sleeves that nest in components on existing access assemblies. The sleeves are offered with different vertical dimensions to accommodate different anticipated degrees of thickening for the surface layer. The sleeves are configured to accommodate the existing covers. Accordingly, changing the construction of an existing access assembly involves removing the cover, installing an appropriately dimensioned sleeve, and replacing the cover on the selected sleeve.
The primary drawback with the latter system is that extension sleeves are held in place primarily by the newly applied asphalt layer. Thus, care has to be taken in compacting the asphalt around the sleeves during resurfacing to make certain the asphalt is tightly compacted against and conformingly around the sleeve. This may require a separate manual process carried out with individual hand tools. Further, regardless of how the compaction is effected, the extension sleeves are prone to being engaged and released by vehicles traveling over the surface. This is particularly a problem when the surface is being treated as by blades on snow removal equipment.
Generally, a number of the above problems, while particularly prevalent during resurfacing, are contended with at the time of initial construction. Given that viable solutions to the above problems are not known to exist, the industry has contended with those problems which, aside from causing inconvenience, potentially represent a danger. For example, the extension sleeves and associated cover, once separated, may remain loose on road surfaces and prone to being struck, and potentially propelled, by vehicular traffic.
Accordingly, there continues to exist a need to devise a practical system that addresses some or all of the above-identified problems.